Estimate, but not calculate exactly. If you're deducting say, taxes for employment throughout the year, and then I carry out some trades that result in capital gains or losses that change me to a different tax bracket, the amount you deducted is now too much or too little, meaning someone's got to pay something at the end.
We DO have withholding measures in place to minimize payment necessary at the end -- but the idea that this can be done as we go fails to take into consideration factors that simply can't be foreseen with certainty.
Never mind the fact that while many people are happy to give up time value in favor of convenience, paying your taxes early means not having that money working for you, in, say, money market funds, or treasury bills, or some other such safe place where it can be held until it is due. Especially with interest rates on the rise, it's not clear that everyone would be particularly thrilled to give up this time value.
We DO have withholding measures in place to minimize payment necessary at the end -- but the idea that this can be done as we go fails to take into consideration factors that simply can't be foreseen with certainty.
Never mind the fact that while many people are happy to give up time value in favor of convenience, paying your taxes early means not having that money working for you, in, say, money market funds, or treasury bills, or some other such safe place where it can be held until it is due. Especially with interest rates on the rise, it's not clear that everyone would be particularly thrilled to give up this time value.